1. Field of the Invention
This invention relates to a bobbin case, and more particularly to a bobbin case on a shuttle around which a rotary hook is rotated.
2. Description of the Prior Art
Conventionally, a bobbin case is divided into an upper portion made of metal and a lower portion made of plastic so as to reduce the overall weight of the bobbin case. The upper portion is connected to the lower portion by screw means or similar connectors. More particularly, a non-tapped hole is provided in the upper portion, a tapped hole in alignment with the non-tapped hole is provided in the lower portion, and a screw is in turn driven into each of the holes. Thus, the upper portion is connected to the lower portion in such manner that the upper portion is fixed between the lower portion and the head of the screw. However, a clearance is formed between the screw and the non-tapped hole, with the result that the screw is brought into contact with the upper portion due to vibration transmitted from a rotary hook upon rotation thereof.